1. Field of the Invention
The present invention relates generally to a projection headlamp system and, more particularly, to one using a light conductor having stepped termination for projecting an improved headlamp light pattern.
2. Description of the Prior Art
It is well known that optical light conductors, such as light guide rods, fibers, or fiber optics, may be used efficiently to carry or conduct the output of a light source to various locations without encountering any substantial transmission losses of the light. The light carried by the optical conductors is confined or condensed to the relatively small dimensions of the conductors themselves and is adaptable for use in various related space restrictive applications in automobiles and aircraft or other vehicles concerned with aerodynamic styling and efficiency.
For example, automotive styling must take into account the amount of frontal area necessary to provide the forward illumination needs for the automobile and provide means to reduce that area, and in particular, the height so as to satisfy aerodynamic considerations. The use of optical light conductors that conduct light within small confines are adaptable to these aerodynamic considerations. Further, optical conductors are advantageously adaptable to provide the overall illumination needs of the vehicle.
To reduce overall space requirements for vehicle forward illumination, one known projection headlamp lighting system employs a remote single central light source to generate light, a light distribution arrangement composed of a plurality of optical light conductors to distribute the light to the various lighting positions, and a light projection arrangement composed of optical elements at the lighting positions to receive the light in the desired pattern. This projection headlamp lighting system is disclosed in U.S. Pat. Nos. 4,811,172 and 4,958,263 issued to Davenport et al and assigned to the same assignee as the present invention. The single central light source can be of the type described in U.S. Pat. No. 4,958,263. The optical light conductors of the distribution arrangement can be a bundle of optical light guide fibers broken out and distributed as necessary. The light projection arrangement of optical elements can be an array of optical connector, lens, and mask elements as described in U.S. Pat. Nos. 4,868,718 and 4,949,227 issued respectively to Davenport et al and Finch et al and assigned to the same assignee as the present invention.
The basic difference between this projection headlamp system using the remote central light source and the traditional headlamp systems is that the end of the light conductor is uniformly bright, whereas in a traditional system there is a brightness gradient from the center of the image of the light source outward to the edge thereof. When the uniformly bright end of the light conductor is imaged on the road, the portion of the image close to the vehicle is too small and too bright while the portions further away are not bright enough.
Consequently, there is a need to improve the projection headlamp system utilizing the remote central light source so as to provide an improved light distribution pattern.